Multi-protocol vehicle relay communication method, gateway device, vehicle network system, transfer method, and non-transitory computer-readable recording medium storing program

ABSTRACT

A network system includes a first network through which a frame of a first type is transmitted in accordance with a first communication protocol and includes a second network in which a frame of a second type is transmitted in accordance with a second communication protocol. A gateway device is connected to the first network and the second network. The gateway device sequentially receives frames of the first type from the first network and determines whether to transmit data regarding the received frames of the first type to the second network. The gateway device transmits, to the second network, a frame of the second type including data regarding a plurality of the frames of the first type determined to be transmitted to the second network when a condition relating to a number of frames of the first type received by the gateway device is satisfied.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. patent application Ser. No. 16/169,039,filed Oct. 24, 2018, which is a continuation of International PatentAppl. No. PCT/JP2017/015814, filed Apr. 20, 2017, which claims thebenefit of U.S. Provisional Patent. Appl. No. 62/342,551, filed May 27,2016, and priority to Japanese Patent Appl. No. 2017-046311, filed Mar.10, 2017. The entire disclosure of each of the above-identifieddocuments, including the specification, drawings, and claims, isincorporated herein by reference in its entirety.

BACKGROUND 1. Technical Field

The present disclosure relates to a message processing technique forrelaying messages between electronic control units that communicate withone another in networks such as vehicle networks.

2. Description of the Related Art

In Japanese Unexamined Patent Application Publication No. 2016-111477, agateway that relays messages between a device according to a CANprotocol and a device according to an Ethernet (registered trademark)protocol or the like is described.

SUMMARY

The above example of the related art requires further improvements.

In one general aspect, the techniques disclosed here feature a gatewaydevice connected to a first network through which a frame of a firsttype is transmitted using the first network in accordance with a firstcommunication protocol and connected to a second network through which aframe of a second type is transmitted in accordance with a secondcommunication protocol, which is different from the first communicationprotocol. The gateway device includes a receiver that sequentiallyreceives frames of the first type from the first network, a processorthat determines whether to transmit data regarding the frames of thefirst type received by the receiver to the second network, and atransmitter that transmits, to the second network, the frame of thesecond type including data regarding a plurality of the frames of thefirst type determined by the processor to be transmitted to the secondnetwork.

According to the present disclosure, further improvements can beachieved.

It should be noted that general or specific embodiments may beimplemented as a system, a method, an integrated circuit, a computerprogram, a storage medium, or any selective combination thereof.

Additional benefits and advantages of the disclosed embodiments willbecome apparent from the specification and drawings. The benefits and/oradvantages may be individually obtained by the various embodiments andfeatures of the specification and drawings, which need not all beprovided in order to obtain one or more of such benefits and/oradvantages.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating the overall configuration of a vehiclenetwork system according to a first embodiment;

FIG. 2 is a diagram illustrating the schematic configuration of vehiclenetworks according to the first embodiment;

FIGS. 3A and 3B are diagrams illustrating formats of a data frame (alsoreferred to as a “CAN frame”) specified in a controller area network(CAN) protocol;

FIG. 4 is a diagram illustrating a format of an Ethernet (registeredtrademark) frame (also referred to as an “E frame”) communicated in apart of the vehicle networks according to the first embodiment;

FIG. 5 is a diagram illustrating an example of the configuration of apayload of an E frame;

FIG. 6 is a configuration diagram of a gateway (gateway device)according to the first embodiment;

FIG. 7 is a diagram illustrating an example of a modification of a frameconfiguration at a time when the gateway according to the firstembodiment transfers a frame;

FIG. 8 is a diagram illustrating an example of transfer rule informationused by the gateway according to the first embodiment;

FIG. 9 is a diagram illustrating an example of a priority transfer listused by the gateway according to the first embodiment;

FIG. 10 is a diagram illustrating a transfer process sequence used bythe gateway according to the first embodiment (continues to FIG. 11);

FIG. 11 is a diagram illustrating the transfer process sequence used bythe gateway according to the first embodiment (continued from FIG. 10);and

FIG. 12 is a diagram illustrating an example of a modification of aframe configuration at a time when a gateway according to a secondembodiment transfers a frame.

DETAILED DESCRIPTION

During these years, a large number of devices called electronic controlunits (ECUs) are provided in a system inside an automobile. A networkconnecting these ECUs with one another is called a vehicle network. Alot of standards exist for vehicle networks. A standard calledcontroller area network (CAN) specified in International Organizationfor Standardization (ISO) 11898-1 is one of major vehicle networks. InCAN, ECUs (nodes) connected to a bus, which is a wired transmission path(communication path), communicate frames (messages). In addition, inCAN, there are no identifiers identifying destinations and sources. Atransmission node transmits each frame with an identifier (CAN-ID) added(i.e., outputs a signal to a bus), and each reception node receives onlymessages having predetermined CAN-IDs (i.e., reads a signal from a bus).In addition, there is a standard called Ethernet (registered trademark)specified in IEEE 802.3 as a standard for transmitting a larger amountof information. A frame (message) in Ethernet (registered trademark)includes information indicating a source and a destination in a headerthereof. In Ethernet (registered trademark), the maximum amount of datatransmitted with a frame is larger than in CAN.

In Japanese Unexamined Patent Application Publication No. 2016-111477, agateway that relays messages between a device according to a CANprotocol and a device according to an Ethernet (registered trademark)protocol or the like is described.

In a vehicle network system including an Ethernet (registered trademark)network and a CAN network, each ECU that communicates with otherelectronic control units includes at least either an Ethernet(registered trademark) interface or a CAN interface. In this case, costundesirably increases if each electronic control unit that needs tocommunicate with an electronic control unit that has an Ethernet(registered trademark) interface and an electronic control unitconnected to a CAN bus (i.e., an electronic control unit including a CANinterface) includes both types of interface. It is therefore desirablefor an electronic control unit including only an Ethernet (registeredtrademark) interface to be able to transmit information to an electroniccontrol unit connected to a CAN bus through a gateway device or thelike. Japanese Unexamined Patent Application Publication No,2016-111477, however, does not describe the configuration of a messageto be transmitted when a gateway device relays (transfers) a messagetransmitted from an electronic control unit connected to a CAN bus(hereinafter also referred to as a “C-ECU”) to an electronic controlunit including an Ethernet (registered trademark) interface (hereinafteralso referred to as a “E-ECU”).

On the basis of the above examination, the present inventors haveconceived aspects of the present disclosure.

A gateway device according to an aspect of the present disclosure is agateway device connected to a first network through which a frame of afirst type is transmitted using the first network in accordance with afirst communication protocol and connected to a second network throughwhich a frame of a second type is transmitted in accordance with asecond communication protocol, which is different from the firstcommunication protocol. The gateway device includes a receiver thatsequentially receives frames of the first type from the first network, aprocessor that determines whether to transmit data regarding the framesof the first type received by the receiver to the second network, and atransmitter that transmits, to the second network, the frame of thesecond type including data regarding a plurality of the frames of thefirst type determined by the processor to be transmitted to the secondnetwork. The gateway device thus transfers (relays) a frame between thenetworks whose communication protocols are different from each other bysequentially receiving a frame of the first type transmitted from an ECU(an electronic control unit of a first type; e.g., a C-ECU) in the firstnetwork such as CAN and transmitting a frame of the second typeincluding data regarding a plurality of frames of the first type to thesecond network. The data regarding the plurality of frames of the firsttype sequentially received from the first network can be stored in abuffer (a storage medium such as a memory) inside or outside the gatewaydevice, for example, until the data is included in the frame of thesecond type and transmitted. By performing such transfer, transmissionefficiency becomes higher than when data regarding a frame of a firsttype is individually transmitted to the second network as the content ofthe frame. That is, with the gateway device, information (data) from anECU (e.g., a C-ECU) connected to the first network can be efficientlytransmitted to an ECU (an electronic control unit of a second type;e.g., an E-ECU) connected to the second network.

In addition, the first network and the second network may be vehiclenetworks. The gateway device may be connected to an Ethernet (registeredtrademark) cable included in the second network. The first communicationprotocol may be a CAN (controller area network) protocol. The secondcommunication protocol may be an Ethernet (registered trademark)protocol. The frame of the first type may include a CAN-ID and, in adata field, data. The frame of the second type may be an Ethernet(registered trademark) frame including an Ethernet (registeredtrademark) header and a payload. The transmitter may transmit the frameof the second type to the second network by outputting the frame of thesecond type to the Ethernet (registered trademark) cable. The frame ofthe second type (E frame) may include the content of a plurality offrames of the first type such as CAN-IDs, for example, as well as data(the content of data fields) regarding the plurality of frames of thefirst type (CAN frames). By relaying a frame with the gateway device, anE-ECU including only an Ethernet (registered trademark) interface, forexample, can efficiently obtain information (data) transmitted from aC-ECU connected to a bus (CAN bus).

In addition, the processor may determine, on a basis of the CAN-ID ofeach of the frames of the first type received by the receiver, whetherto transmit data regarding the frames of the first type to the secondnetwork. As a result, among CAN frames transmitted through the bus, onlyCAN frames having a CAN-ID specified in advance as a CAN-ID to bereceived by an E-ECU, for example, can be transmitted to the E-ECU. Dataregarding unnecessary CAN frames, therefore, is not transferred to thesecond network.

In addition, the processor may also refer to reference information inwhich a plurality of destinations is associated with CAN-IDs and select,on the basis of the CAN-ID of each of the frames of the first typereceived by the receiver, one of the plurality of destinations as adestination of the data regarding the plurality of the frames of thefirst type to be transmitted to the second network. The transmitter maytransmit, to the second network, the frame of the second type includingthe data regarding the plurality of the frames of the first type whosedestinations selected by the processor are same. The destinations may bea single E-ECU or a plurality of E-ECUs of the same type (may be asubnetwork or the like to which these E-ECUs are connected). As aresult, since data regarding CAN frames is transmitted using a frame ofthe second type (E frame) including a plurality of pieces of data whosedestinations are the same, the data regarding the CAN frames can beefficiently transmitted to the destination E-ECU(s) and the like.

In addition, the frame of the second type transmitted by the processormay include destination information indicating the same destinationsselected by the processor. As a result, an E frame need not bebroadcast, for example, and can be efficiently transmitted to adestination indicated by destination information.

In addition, in the reference information, a plurality of media accesscontrol (MAC) addresses as the plurality of destinations may beassociated with the CAN-IDs. The frame of the second type transmitted bythe transmitter may include the data regarding the plurality of theframes of the first type having the same destinations selected by theprocessor in the payload, a MAC address, which is the same destinations,and a destination MAC address in an Ethernet (registered trademark)header. As a result, an E frame whose destination can be checked with aheader is transmitted to the second network. Efficient transmission,therefore, becomes possible by referring to the header using a networkhub (e.g., a switching hub) or the like and selecting a transfer pathbefore the E frame reaches a destination E-ECU.

In addition, the processor may refer to reference information in which aplurality of destinations is associated with the CAN-IQs and select, onthe basis of the CAN-ID of each of the frames of the first type receivedby the receiver, one of the plurality of destinations as a destinationof the data regarding the plurality of the frames of the first type tobe transmitted to the second network. The transmitter may transmit theframe of the second type including the data regarding the plurality ofthe frames of the first type determined by the processor to betransmitted to the second network and transmit destination informationindicating the destination selected by the processor in the payload. Asa result, a plurality of pieces of data to be transmitted to differentdestinations are included in a single E frame along with destinationinformation and transmitted to the second network. Consequently,transmission efficiency before an E frame reaches a relay device or thelike that divides data included in the E frame for destinations and thattransmits the E frame to the destinations in the second network, forexample, can be increased. The E frame, for example, may be broadcastand transmitted to E-ECUs, instead. In this case, the E-ECUs may extractnecessary data from the E frame on the basis of the destinationinformation and use the data.

In addition, the gateway device may be connected to a plurality of busesof the first network. The plurality of destinations, the plurality ofbuses, and the CAN-IDs may be associated in the reference information.The processor may refer to the reference information and select, on thebasis of the CAN-ID and a source bus of each of the frames of the firsttype received by the receiver, one of the plurality of destinations asthe destination of the data regarding the plurality of the frames of thefirst type to be transmitted to the second network. As a result, whenassociations between CAN-IDs of CAN frames and destinations are definedfor each bus (CAN bus) as the reference information, data regarding aCAN frame can be appropriately transmitted to any E-ECU even if thereare a plurality of buses.

In addition, the gateway device may be connected to a plurality ofEthernet (registered trademark) cables. The processor may refer toreference information in which the plurality of cables is associatedwith CAN-IDs and select, on the basis of the CAN-ID of each of theframes of the first type received by the receiver, one of the pluralityof Ethernet (registered trademark) cables as a destination of the dataregarding the plurality of the frames of the first type to betransmitted to the second network. The transmitter may transmit theframe of the second type including the data regarding the plurality ofthe frames of the first type whose Ethernet (registered trademark)cables selected by the processor as destinations are same, to the one ofthe plurality of Ethernet (registered trademark) cables. As a result,since a plurality of pieces of data regarding CAN frames determined tobe transmitted to the same Ethernet (registered trademark) cable can beincluded in an E frame output to the cable, efficient transmissionbecomes possible.

In addition, in the frame of the second type, the data regarding theplurality of the frames of the first type determined by the processor tobe transmitted to the second network may be arranged in order ofpredetermined priority levels of CAN-IDs based on CAN-IDs of theplurality of the frames of the first type. As a result, an E-ECU thathas received a frame of the second type (E frame) can perform processingin consideration of priority levels of pieces of data included in the Eframe.

In addition, in the frame of the second type, the data regarding theplurality of the frames of the first type determined by the processor tobe transmitted to the second network may be arranged in order ofreception by the receiver. As a result, an E-ECU that has received aframe of the second type (E frame) can perform processing inconsideration of order in which pieces of data included in the E framehave been transmitted to a bus (CAN bus).

In addition, the transmitter may transmit the frame of the second typeincluding the data regarding the plurality of the frames of the firsttype when a condition relating to a number of frames of the first typereceived by the receiver is satisfied. As a result, efficient datatransmission can be achieved by appropriately setting the certaincondition in consideration of transmission efficiency of a frame of thesecond type.

In addition, the transmitter may transmit the frame of the second typewhen a condition relating to time is satisfied as a result of countingof the time. As a result, appropriate data transmission can be achievedby appropriately setting the certain condition in consideration of; forexample, a balance between transmission efficiency and transmissiondelay.

In addition, when the CAN-ID of one of the frames of the first typereceived by the receiver is a particular ID, the transmitter maytransmit, to the second network, a frame of the second type includingdata regarding the one of the frames of the first type having theparticular ID even when the certain condition is not satisfied. As aresult, priority transfer (transfer without delay) of importantinformation can be achieved, for example, by setting a CAN-ID of a CANframe including important data (information) as a particular ID.

In addition, when transmitting the frame of the second type includingthe data regarding the one of the frames of the first type having theparticular ID, the transmitter may: transmit the frame of the secondtype and include data regarding a second one of the frames of the firsttype that does not have the particular ID and that has been determinedby the processor to be transmitted to the second network and has not yetbeen transmitted; or transmit another frame of the second type includingthe data regarding the second one of the frames of the first type thatdoes not have the particular ID and that has been determined by theprocessor to be transmitted to the second network and has not yet beentransmitted. As a result, when data (e.g., important data) regarding aCAN frame having a CAN-ID that is the particular ID received by thegateway device is transferred (transmitted) in a prioritized manner,data regarding a CAN frame having another CAN-ID received by the gatewaydevice is transmitted. An E-ECU connected to the second network,therefore, can process the data (e.g., important data) regarding the CANframe having the particular ID in consideration of a relationship withthe data regarding the other CAN frame.

In addition, a vehicle network system according to an aspect of thepresent disclosure may include a plurality of electronic control unitsof a first type connected to a first network through which a frame of afirst type is transmitted in accordance with a first communicationprotocol; an electronic control unit of a second type connected to asecond network through which a frame of a second type is transmitted inaccordance with a second communication protocol, which is different fromthe first communication protocol; and a gateway device connected to thefirst network and the second network. The gateway device includes areceiver that sequentially receives frames of the first type from thefirst network, a processor that determines whether to transmit dataregarding the frames of the first type received by the receiver to thesecond network, and a transmitter that transmits, to the second network,the frame of the second type including data regarding a plurality of theframes of the first type determined by the processor to be transmittedto the second network. As a result, an ECU (e.g., a C-ECU) connected toa bus of the first network such as CAN can efficiently transmitinformation to an ECU (e.g., an E-ECU) connected to the second networksuch as Ethernet (registered trademark).

In addition, a transfer method according to an aspect of the presentdisclosure is a transfer method of a gateway device connected to a firstnetwork through which a frame of a first type is transmitted using thefirst network in accordance with a first communication protocol andconnected to a second network through which a frame of a second type istransmitted in accordance with a second communication protocol, which isdifferent from the first communication protocol. The transfer methodincludes sequentially receiving frames of the first type from the firstnetwork, determining, by a processor, whether to transmit data regardingthe frames of the first type received in the receiving to the secondnetwork, and transmitting, to the second network, the frame of thesecond type including data regarding a plurality of the frames of thefirst type determined by the processor in the determining to betransmitted to the second network. As a result, an ECU connected to thebus of the first network can efficiently transfer a frame to the secondnetwork.

In addition, a program according to an aspect of the present disclosureis a program for causing a gateway device that is connected to a firstnetwork through which a frame of a first type is transmitted using thefirst network in accordance with a first communication protocol andconnected to a second network through which a frame of a second type istransmitted in accordance with a second communication protocol, which isdifferent from the first communication protocol, to perform operationsincluding sequentially receiving frames of the first type from the firstnetwork, determining whether to transmit data regarding the frames ofthe first type received in the receiving to the second network, andtransmitting, to the second network, the frame of the second typeincluding data regarding a plurality of the frames of the first typedetermined in the determining to be transmitted to the second network.When the program is installed on the gateway device connected to the busof the first network and the second network and including themicroprocessor and executed, the gateway device can appropriately relay(transfer) information from an ECU (e.g., a C-ECU) connected to the busof the first network to the second network.

It should be noted that these general or specific aspects may beimplemented as a system, a method, an integrated circuit, a computerprogram, a computer-readable recording medium such as a CD-ROM, or anyselective combination thereof.

A vehicle network system including a gateway device (gateway) andelectronic control units (ECUs) according to each embodiment will bedescribed hereinafter with reference to the drawings. The followingembodiments are specific examples of the present disclosure. Values,components, arrangement and connection modes of the components, steps(processes), and the order of the steps mentioned in the followingembodiments, therefore, are examples and do not limit the presentdisclosure. Among the components described in the following embodiments,ones not described in the independent claims are components that may bearbitrarily added. The drawings are schematic diagrams and notnecessarily strict illustrations.

First Embodiment

A vehicle network system 10 including a plurality of electronic controlunits (ECUs) that communicate data through vehicle networks and agateway will be described hereinafter with reference to the drawings asan embodiment of the present disclosure.

1.1 Overall Configuration of Vehicle Network System 10

FIG. 1 illustrates the overall configuration of the vehicle networksystem 10 according to a first embodiment.

The vehicle network system 10 is a network communication system in avehicle provided with various devices such as control devices, sensors,actuators, and user interfaces. The vehicle network system 10 includes,as the vehicle networks, a first network (CAN network) in which dataframes (CAN frames) and the like are transmitted in accordance with aCAN protocol using buses and a second network (Ethernet (registeredtrademark) network) through which Ethernet (registered trademark) frames(E frames) are transmitted in accordance with an Ethernet (registeredtrademark) protocol.

As illustrated in FIG. 1, the vehicle network system 10 is configured byincluding a gateway 100, electronic control units (E-ECUs) 200 a to 200c, a network hub 400 (also referred to as an “E-hub”), electroniccontrol units (C-ECUs) 500 a to 500 d, various devices (an in-vehicleinfotainment (IVI) 300 a, a rear camera 300 b, a radar 300 c, an engine600 a, a brake 600 b, a door open/close sensor 600 c, and a windowopen/close sensor 600 d) connected to the electronic control units (theE-ECUs and the C-ECUs), cables (Ethernet (registered trademark) cables)20 a to 20 d, and buses (CAN buses) 30 a and 30 b. The buses 30 a and 30b are communication paths for the first network, and the Ethernet(registered trademark) cables 20 a to 20 d are communication paths forthe second network.

The vehicle network system 10 can include a number of ECUs other thanthe E-ECUs 200 a to 200 c and the C-ECUs 500 a to 500 d. In addition tothe C-ECUs 500 a to 500 d, C-ECUs that are not illustrated, for example,can be connected to the buses 30 a and 30 b.

The ECUs (the E-ECUs and the C-ECUs) are, for example, devices includingprocessors (microprocessors), digital circuits such as memories, analogcircuits, communication circuits, and the like. The memories areread-only memories (ROMs), random-access memories (RAMs), and the likeand capable of storing programs (computer programs as software) to beexecuted by the processors. A nonvolatile memory may be included as amemory. The ECUs achieve various functions, for example, when theprocessors operate in accordance with the programs (computer programs).Each computer program is configured by combining a plurality ofinstruction codes indicating commands to a corresponding processor inorder to achieve certain functions.

The C-ECUs 500 a to 500 d communicate frames in accordance with the CANprotocol. The C-ECUs 500 a to 500 d are connected to the engine 600 a,the brake 600 b, the door open/close sensor 600 c, and the windowopen/close sensor 600 d, respectively. The C-ECUs 500 a to 500 d obtainstates of the corresponding devices and, for example, periodicallytransmit data frames indicating the states to the first networkincluding the buses 30 a and 30 b and the like. The C-ECUs 500 a to 500d receive data frames from the buses included in the first network,interpret the data frames, and determine whether the data frames includeCAN-IDs to be received. The C-ECUs 500 a to 500 d can control thedevices connected thereto in accordance with data (the content of datafields) of the frame frames as necessary, or generate and transmit dataframes as necessary.

The gateway 100 is a kind of ECU as a gateway (a relay device or thelike) connected to the buses 30 a and 30 b and the cable 20 d. Thegateway 100 includes a processor, a digital circuit such as a memory, ananalog circuit, a communication circuit, and the like. The gateway 100has a function of transferring (relaying) a frame received from acommunication path (a bus or a cable) to another communication path. Thetransfer of a frame performed by the gateway 100 is relaying (i.e.,reception and transmission) of data (information) regarding a frame andcan accompany conversion of a communication method, a frame format, andthe like for a communication protocol employed by a destinationcommunication path. In addition, as the transfer of a frame betweencommunication paths, the gateway 100 can receive one or a plurality offrames from one or a plurality of communication paths and transmit theone or plurality of frames to one or a plurality of communication paths.In the present embodiment, a transfer function of the gateway 100, bywhich data regarding a CAN frame received from a CAN bus of the firstnetwork is transmitted to another CAN bus of the first network or acable of the second network, will be focused upon.

The E-ECUs 200 a to 200 c include Ethernet (registered trademark)interfaces and are connected to the Ethernet (registered trademark)cables. The E-ECUs 200 a to 200 c transmit or receive Ethernet(registered trademark) frames (E frames) in accordance with the Ethernet(registered trademark) protocol. The E-ECUs 200 a to 200 c are connectedto the IVI 300 a, the rear camera 300 b, and the rear camera 300 c,respectively, and perform processes based on information obtained fromthe corresponding devices. The E-ECUs 200 a to 200 c can control thecorresponding devices as necessary, or transmit information to otherECUs as necessary. The IVI 300 a is a device including a display andhaving multimedia functions such as playback of images, sounds, and thelike and a communication function, by which the IVI 300 a communicateswith a server 90 outside the vehicle through an external network 91 suchas the Internet. The server 90 is, for example, a computer having afunction of providing information for the ECUs in the vehicle and thelike.

The E-hub 400 is an Ethernet (registered trademark) switch (switchinghub) connected to the gateway 100 and the E-ECUs 200 a to 200 c. TheE-hub 400 includes, for example, a digital circuit such as a memory, ananalog circuit, a communication circuit, and the like.

1.2 Configuration of Vehicle Networks

FIG. 2 illustrates the schematic configuration of the vehicle networksaccording to the present embodiment.

In the vehicle network system 10, the C-ECUs 500 a to 500 d cancommunicate with one another through the first network, which includesthe buses 30 a and 30 b, the gateway 100, and the like. The gateway 100and the E-ECUs 200 a to 200 c each include a unique MAC address and cancommunicate with one another through the second network, which isconfigured by connecting the cables through the E-hub 400. The E-hub 400holds a MAC address table, for example, and, if receiving an E frame,learns a MAC address corresponding to a connection terminal (port) ofeach cable. The E-hub 400 also selects a destination port on the basisof a destination MAC address in a header of the received E frame inaccordance with the MAC address table and outputs the E frame to a cableconnected to the destination port to transfer the E frame.

The gateway 100 includes a port (i.e., a terminal to which an Ethernet(registered trademark) cable is connected) for connecting to the secondnetwork and a plurality of ports (connection terminals) for connectingto the bus 30 a (also referred to as a “first CAN bus”) and the bus 30 b(also referred to as a “second CAN bus”) of the first network.Information output from the C-ECU 500 a, for example, can be transmittedto the E-ECU 200 a through the bus 30 a, the gateway 100, the cable 20d, the E-hub 400, and the cable 20 a under a certain condition.

1.3 Configuration of Frames Communicated in Vehicle Network

In the first network, the C-ECUs 500 a to 500 d and the like communicateframes in accordance with the CAN protocol. Frames in the CAN protocolinclude a data frame, a remote frame, an overload frame, and an errorframe. Here, the data frame will be mainly focused upon. FIGS. 3A and 3Billustrate formats of a data frame (CAN frame) communicated in the firstnetwork. FIG. 3A illustrates a standard format. In the standard format,a data frame includes a start of frame (SOF), an ID (CAN-ID), a remotetransmission request (RTR), an identifier extension (IDE), a reservedbit “r”, size, data, a cyclic redundancy check (CRC) sequence, a CRCdelimiter “DEL”, an acknowledgement (ACK) slot, an ACK delimiter “DEL”,and an end of frame (EOF). Here, the ID (CAN-ID) as the content of an IDfield is an identifier indicating a type of data and also called amessage ID. In CAN, communication mediation, in which a frame having asmaller CAN-ID takes priority, is performed when a plurality of nodeshave simultaneously started to perform transmission. The size is a datalength code (DLC) indicating the length of a subsequent data field(data). Specifications of data (the content of the data field) are notspecified in the CAN protocol but specified by the vehicle networksystem 10. The specifications of data, therefore, depend on a vehiclemodel, a manufacturer (manufacturing maker), and the like. FIG. 3Billustrates an enhanced format. Although the first network employs thestandard format in the present embodiment, when the first networkemploys the enhanced format, 29 bits, which is the sum of an 11-bit baseID (a part of a CAN-ID) of an ID field and an 18-bit enhanced ID (therest of the CAN-ID), may be treated as a CAN-ID.

FIG. 4 illustrates a format of a frame (E frame) communicated in thesecond network. As illustrated in the figure, the E frame is configuredby adding a header (Ethernet (registered trademark) header) before apayload storing data, which is main transmission content. The headerincludes a destination MAC address, a source MAC address, and a type.

When the gateway 100 in the vehicle network system 10 transfers a CANframe received from a CAN bus to the second network connected to theE-ECUs, the gateway 100 transmits an E frame including a plurality ofpieces of CAN frame information. The CAN frame information isinformation extracted from a data frame (CAN frame) transmitted througha CAN bus. The CAN frame includes at least the content of a data field(data) and can include, for example, a CAN-ID and size.

FIG. 5 illustrates an example of the data configuration of the payloadof the E frame illustrated in FIG. 4. In the example illustrated in FIG.5, CAN frame information includes a CAN-ID, size, and data. The numberof messages (MSG) illustrated in FIG. 5 indicates the number of piecesof CAN frame information. Information indicating the total amount ofdata of the CAN frame information may be used instead of the number ofmessages. A CAN flag is an identification flag for identifying whetherthe E frame includes information transmitted from the first network(i.e., CAN frame information). The CAN flag is turned on when thepayload of the E frame includes CAN frame information and turned off inother cases (i.e., values indicating information contrary to on).Although an example in which a CAN flag is arranged at a beginning of anE frame is illustrated in FIG. 5, this is just an example. By includinga plurality of pieces of CAN frame information in a payload of an Eframe as in the example of FIG. 5, for example, transmission efficiencycan improve.

1.4 Configuration of Gateway 100

FIG. 6 is a configuration diagram of the gateway 100. As illustrated inFIG. 6, the gateway 100 is configured by including a C communicationunit 110 a, a C communication unit 110 b, an E communication unit 120, atransfer rule holding unit 130, and a transfer control unit 140. Thesecomponents are achieved in the gateway 100 by communication circuits, amemory, a digital circuit, a processor that executes programs stored inthe memory.

The C communication unit 110 a is a communication circuit or the likeconnected to the bus 30 a included in the first network and includes areception section 111 a that sequentially receives CAN frames from thebus 30 a and a transmission section 112 a that transmits CAN frames tothe bus 30 a.

The C communication unit 110 b is a communication circuit or the likeconnected to the bus 30 b included in the first network and includes areception section 111 b that sequentially receives CAN frames from thebus 30 b and a transmission section 112 b that transmits CAN frames tothe bus 30 b.

The E communication unit 120 is a communication circuit or the likeconnected to the cable 20 d (a wired communication path connected to theE-hub 400) included in the second network and includes a receptionsection 121 that receives E frames from the cable 20 d and atransmission section 122 that transmits E frames to the cable 20 d.

The transfer rule holding unit 130 is achieved by a storage medium suchas a memory and holds reference information, which specifies a frametransfer condition and the like. The reference information is, forexample, transfer rule information in which CAN-IDs to be transferred,source buses, and destinations (MAC addresses, etc.) are associated withone another, a priority transfer list in which CAN-IDs having priorityin transfer, source buses, and destinations are associated with eachother, or the like.

The transfer control unit 140 is achieved, for example, by a processoror the like that executes programs. The transfer control unit 140determines whether to transfer a received frame and performs controlrelating to transfer in accordance with a result of the determination.The control relating to transfer is, for example, control in which the Ecommunication unit 120 is caused to transmit, to the cable 20 d, an Eframe including a plurality of pieces of CAN frame information in apayload on the basis of a plurality of sequentially received CAN frames.FIG. 7 illustrates an image of the gateway 100 transmitting an E frameon the basis of a plurality of received CAN frames (CAN frames 1 to N).As illustrated in the figure, when transferring the frame, the gateway100 changes the configuration of the frame. A payload of the E frame tobe transmitted includes, for example, N, which is a predeterminednumber, pieces of CAN frame information. Data regarding the N pieces ofCAN frame information is the content (data) of data fields of N receivedCAN frames or the like. The content of CAN frames that have beenreceived and are waiting for transfer are, for example, stored in astorage medium (buffer) such as the memory of the gateway 100. The Eframe including the N pieces of CAN frame information illustrated inFIG. 7 is to be received, for example, by a destination E-ECU (e.g.,E-ECU 200 a) through the E-hub 400. A MAC address of the gateway 100 isset to a header of the E frame as a source MAC address, and a CAN flagthat has been turned on, which indicates that CAN frame information isincluded, is set to the payload of the E frame. A MAC address of thedestination E-ECU is set as a destination MAC address of the E frame inaccordance with the transfer rule information or the like held by thetransfer rule holding unit 130.

The transfer control unit 140 includes a determination section 141 and aframe construction section 142. The transfer control unit 140 controls atransmission unit (the transmission section 122, the transmissionsection 112 a, or the transmission section 112 b) under a certaincondition in accordance with a result of a determination or the likemade by the determination section 141 and causes the transmission unitto transmit a frame.

The determination section 141 determines whether to transmit, to thesecond network, data regarding a CAN frame received by the receptionsection 111 a or the reception section 111 b on the basis of a CAN-ID.The determination is made, for example, in accordance with thepredetermined reference information regarding CAN-IDs. The determinationsection 141 also selects a destination of the data regarding the CANframe in accordance with the reference information. The determinationwhether to transmit a CAN frame to the second network and the selectionof a destination of a frame (an E frame or a CAN frame) including dataregarding the CAN frame are performed, for example, using the transferrule information indicating CAN-IDs or the like of one or more CANframes whose data is to be transmitted to the second network.

FIG. 8 illustrates an example of the transfer rule information as thereference information held by the transfer rule holding unit 130 andreferred to by the determination section 141 of the transfer controlunit 140. As illustrated in the figure, the transfer rule information isinformation in which, for example, sources, CAN-IDs to be transferred,destination network types, and destination identification informationare associated with one another. As the destination network types, Eindicates the second network (E network), and CAN indicates the firstnetwork. The E network is the second network through which communicationis performed in accordance with the Ethernet (registered trademark)protocol. When the destination network type is the E network, thedestination identification information is a MAC address, and when thedestination network type is CAN, the destination identificationinformation is information for identifying a bus. The transfer ruleinformation in the example illustrated in FIG. 8 indicates that when aCAN frame that has been received from the first CAN bus and whose CAN-IDis 0x400, 0x500, or 0x600 is to be transferred, the destination networktype is CAN, and the CAN frame is to be transmitted to the second CANbus among the plurality of CAN buses connected. The transfer ruleinformation also indicates that all CAN frames received from the secondCAN bus are to be transmitted to the first CAN bus. In addition, thetransfer rule information indicates that when a CAN frame that has beenreceived from the first CAN bus and whose CAN-ID is 0x100, 0x01, or0x102 is to be transferred, the destination network type is the Enetwork. CAN frame information, therefore, is to be stored in an Eframe, and the E frame is to be transmitted with a destination MACaddress thereof set as 00:11:22:33:44:55 (e.g., a MAC address of theE-ECU 200 a).

The determination section 141 determines whether a bus that has receiveda CAN frame is the first CAN bus (bus 30 a) or the second CAN bus (bus30 b). The determination section 141 then compares the bus with sourcesin the transfer rule information and a CAN-ID of the CAN frame withCAN-IDs to be transferred in the transfer rule information. If anapplicable combination of a source and a CAN-ID to be transferred isfound as a result of the comparison, the determination section 141identifies a destination network type and destination identificationinformation corresponding to the combination to select a destination ofa frame based on the received CAN frame. If no applicable combination ofa source and a CAN-ID to be transferred is found as a result of thecomparison, the determination section 141 determines that the receivedCAN frame is not to be transmitted to the first or second network. Ifthe destination network type indicates the E network in the selection ofthe destination, the determination section 141 determines that thereceived CAN frame is to be transmitted to the second network. In thiscase, the determination section 141 selects one of a plurality of MACaddresses as the destination identification information in the transferrule information as a destination of an E frame including data and thelike (CAN frame information) regarding the CAN frame to be transmittedto the second network. The reference information referred to by thedetermination section 141 may be, for example, a combination of areception ID list indicating whether a CAN-ID is to be transferred andtransfer rule information in which CAN-IDs to be transferred anddestinations are associated with each other. Any type of referenceinformation may be used. That is, the reference information may be alist of CAN-IDs not to be transferred, or may be a function or the likefor determining whether a CAN-ID is to be transferred, instead. Adestination (e.g., destination identification information indicated bythe transfer rule information) in the reference information may be a MACaddress, another type of identification information regarding an E-ECU(e.g., an Internet protocol (IP) address, etc.), or an addressindicating a subnetwork to which a plurality of E-ECUs of the same typeare connected.

If the determination section 141 determines that a plurality ofsequentially received CAN frames are to be transmitted to the secondnetwork, the frame construction section 142 connects data (CAN frameinformation) regarding a plurality of (e.g., a predetermined number,namely N) CAN frames whose destinations selected by the determinationsection 141 are the same (e.g., the destinations are a MAC address ofthe same E-ECU) and turns on a CAN flag to construct an E frame (referto FIG. 7). In this case, the frame construction section 142 sets theMAC address (a MAC address indicated by the destination identificationinformation in the transfer rule information) of the destination as adestination MAC address in a header of the E frame. In this case, thetransfer control unit 140 causes the transmission section 122 of the Ecommunication unit 120 to output the E frame constructed by the frameconstruction section 142 to the cable 20 d. When destinations areindicated by IP addresses of E-ECUs in the reference information, theframe construction section 142 may provide an IP header for a payload ofthe E frame (e.g., insert the IP header before the CAN flag illustratedin FIG. 7) and include an IP address of a destination E-ECU as adestination IP address of the IP header. The frame construction section142 may then set a MAC address found on the basis of the IP address ofthe destination E-ECU as the destination MAC address of the E frame.

The frame construction section 142 may arrange a plurality of pieces ofCAN frame information in any order when connecting the plurality ofpieces of CAN frame information and setting the plurality of pieces ofCAN frame information in a payload of an E frame, but the followingmethod, for example, is effective. That is, CAN frame information (dataand the like) regarding each of a plurality of CAN frames determined bythe determination section 141 to be transmitted to the second network isarranged in an E frame in order of reception by the reception section111 a or 111 b. With this method, an E-ECU that has received, throughthe E-hub 400, an E frame transmitted to the gateway 100 can performprocessing in consideration of the order in which data included in the Eframe has been transmitted to a CAN-bus. In another method, CAN frameinformation (data and the like) regarding each of a plurality of CANframes determined by the determination section 141 to be transmitted tothe second network is arranged in an E frame in order of predeterminedpriority levels of CAN-IDs based on CAN-IDs of the CAN frames. Apredetermined priority level of a CAN-ID becomes higher, for example, asthe CAN-ID increases as in the communication mediation between the CANbuses. With this method, an E-ECU that has received, through the E-hub400, an E frame transmitted to the gateway 100 can perform processingbased on the order of priority (e.g., the order of importance, etc.) ofdata included in an E frame.

If the determination section 141 selects either the first CAN bus or thesecond CAN bus as a destination of a CAN frame received from the otherof the first CAN bus and the second CAN bus, the transfer control unit140 controls a transmission section (the transmission section 112 a orthe transmission section 112 b) such that the transmission sectiontransmits the received CAN frame to the other of the first CAN bus andthe second CAN bus as it is.

If the determination section 141 selects an E-ECU (i.e., a MAC addressof the E-ECU) as a destination of a CAN frame received from a CAN bus,the transfer control unit 140 causes the frame construction section 142to construct an E frame and the transmission section 122 to transmit theE frame when a certain condition relating to the number of CAN framesreceived by a reception section (the reception section 111 a or thereception section 111 b) has been satisfied for CAN frames whosedestinations are the same. The certain condition relating to the numberof CAN frames received is that, for example, N CAN frames whosedestinations are the same be received (e.g., a CAN frame whose CAN frameinformation is to be included in an E frame for a destination bereceived N times after a previous E frame for the destination istransmitted). Alternatively, the certain condition relating to thenumber of CAN frames received may be that a total of M bytes of CANframes whose CAN frame information is to be included in an E frame for adestination be received after a previous E frame for the destination istransmitted.

When a CAN-ID of a CAN frame received from a CAN bus is a particular ID,the transfer control unit 140 causes the frame construction section 142to construct an E frame including CAN frame information (data and thelike) regarding the CAN frame having the particular ID and thetransmission section 122 to immediately transmit the E frame to thesecond network even if the certain condition relating to the number ofCAN frames received is not satisfied. The particular ID is, for example,a CAN-ID having priority in transfer described in the priority transferlist as the reference information held by the transfer rule holding unit130.

FIG. 9 illustrates an example of the priority transfer list as thereference information used by the transfer control unit 140. Asillustrated in the figure, the priority transfer list is information inwhich, for example, sources, CAN-IDs having priority in transfer,destination network types, and destination identification informationare associated with one another. The priority transfer list illustratedin FIG. 9 indicates, for example, that a CAN frame that has beenreceived from the first CAN bus and whose CAN-ID is 0x100 be transferredto an E-ECU whose MAC address is 00:11:22:33:44:55 (e.g., the E-ECU 200a) without delay. If the transfer control unit 140 receives a CAN framewhose CAN-ID is 0x100 from the first CAN bus, therefore, the transfercontrol unit 140 causes the transmission section 122 to immediatelytransmit an E frame including CAN frame information, which is data andthe like regarding the CAN frame, in a payload.

More specifically, the transfer control unit 140 determines whether abus that has received the CAN frame is the first CAN bus (bus 30 a) orthe second CAN bus (bus 30 b). The transfer control unit 140 thencompares the bus with sources in the priority transfer list and a CAN-IDof the CAN frame with CAN-IDs having priority in transfer in thepriority transfer list. If an applicable combination of a source and aCAN-ID having priority in transfer is found as a result of thecomparison, the transfer control unit 140 identifies destinationidentification information corresponding to the combination to select adestination of an E frame based on the received CAN frame. A CAN-IDhaving priority in transfer (i.e., a particular ID) in the prioritytransfer list is, for example, a predetermined CAN-ID (errornotification ID) for a CAN frame indicating an abnormality in drivingcontrol of the vehicle. When the gateway 100 promptly transmits, to theE-ECU 200 a or the like, a CAN frame having the error notification IDtransmitted from a C-ECU, for example, a display of the IVI 300 aconnected to the E-ECU 200 a can promptly display a warning screen basedon information regarding an error notification. An accident, therefore,can be effectively prevented. If CAN-IDs of CAN frames relating to thedriving control of the vehicle such as driving, turning, and stoppingare set as particular IDs in addition to the error notification ID,E-ECUs can promptly display information relating to the driving control,and safe driving of the vehicle can be effectively achieved. Thetransfer control unit 140 may determine particular IDs using any methodinstead of the one employing the priority transfer list. For example,the transfer control unit 140 may determine all CAN-IDs having valuesequal to or smaller than a predetermined threshold as particular IDs.

In addition, when the transfer control unit 140 causes the transmissionsection 122 to transmit an E frame including CAN frame informationregarding a CAN frame having a particular ID, the transfer control unit140 may cause the frame construction section 142 to generate another Eframe including CAN frame information (data and the like) regarding oneor a plurality of CAN frames that do not have a particular ID and thathave been determined by the determination section 141 to be transmittedto the second network but have not yet been transmitted and thetransmission section 122 to transmit the E frame. Alternatively, thetransfer control unit 140 may cause the frame construction section 142to further include CAN frame information regarding a CAN frame that doesnot have a particular ID and that has been determined by thedetermination section 141 to be transmitted to the second network buthas not yet been transmitted in an E frame including CAN frameinformation regarding a CAN frame having a particular ID and constructan E frame and the transmission section 122 to transmit the E frame.More specifically, when a CAN-ID having priority in transfer (i.e., aparticular ID) is 0x100 as in the example illustrated in FIG. 9 and thetransfer control unit 140 has received a CAN frame having a CAN-ID of0x100, the transfer control unit 140 may transmit, if CAN frames whosedestinations are the same (MAC address 00:11:22:33:44:55) areaccumulated and waiting for satisfaction of the certain conditionrelating to the number of CAN frames received (i.e., waiting foraccumulation of N CAN frames), an E frame obtained by connecting CANframe information regarding the accumulated CAN frames and CAN frameinformation regarding the CAN frame having the particular ID (0x100) toeach other and including the connected CAN frame information in apayload.

In addition, the transfer control unit 140 may have a transmissioncontrol function of generating a CAN frame on the basis of the contentof an E frame received by the reception section 121 of the Ecommunication unit 120 and causing the transmission section 112 a or thetransmission section 112 b to transmit the CAN frame to a CAN bus.

The transmission section 122 transmits, to the second network (i.e., thecable 20 d), an E frame including data regarding a plurality of CANframes determined by the determination section 141 to be transmitted tothe second network under control performed by the transfer control unit140. More specifically, the transmission section 122 transmits an Eframe including CAN frame information regarding a plurality of CANframes for which the same destination has been selected by thedetermination section 141 to the destination if the certain conditionrelating to the number of CAN frames received, whose CAN frameinformation is included in the E frame, is satisfied. Even while thecertain condition is not satisfied, the transmission section 122transmits, if a CAN frame having a particular ID is received, an E frameincluding CAN frame information regarding the CAN frame. When thetransmission section 122 transmits an E frame including CAN frameinformation regarding a CAN frame having a particular ID, thetransmission section 122 transmits the E frame while including, in the Eframe, CAN frame information regarding a CAN frame that does not have aparticular ID and that has been determined by the determination section141 to be transmitted to the second network but has not yet beentransmitted or transmits the E frame while including the CAN frameinformation in another E frame.

1.5 Operation of Gateway 100

FIGS. 10 and 11 illustrate a specific example of a transfer processsequence relating to transfer of a CAN frame performed by the gateway100. The transfer process sequence illustrated in FIGS. 10 and 11indicates a transfer process achieved by cooperation between the Ccommunication unit 110 a, the transfer control unit 140, the Ccommunication unit 110 b, and the E communication unit 120 of thegateway 100. Here, the transfer of a CAN frame is transmission of a CANframe that has been received or transmission of an E frame including CANframe information regarding one or plurality of received CAN frames. Atransfer process performed by the gateway 100 when a CAN frame receivedfrom the first CAN bus (bus 30 a) of the first network is transferred tothe second CAN bus (bus 30 b) or the second network (E network) will bedescribed hereinafter with reference to FIGS. 10 and 11. The transferprocess starts when the gateway 100 has received a CAN frame from a CANbus.

The C communication unit 110 a connected to the first CAN bus receives,with the reception section 111 a, a CAN-ID from the first CAN bus anddetermines whether the CAN-ID is to be received (step S1). Thedetermination is made, for example, by referring to a reception ID listenumerating CAN-IDs to be received. The determination section 141 of thetransfer control unit 140 may make the determination instead of thereception section 111 a, which makes the determination on the basis ofthe reception ID list. In this case, the determination section 141determines whether the CAN-ID is to be received (whether the CAN-ID isto be transferred) on the basis of the reception ID list of the transferrule information.

If the C communication unit 110 a determines in step S1 that the CAN-IDis to be received, the reception section 111 a of the C communicationunit 110 a receives a corresponding CAN frame (step S2) and transmitsthe CAN frame to the transfer control unit 140 (step S3).

The transfer control unit 140 obtains and refers to the transfer ruleinformation held by the transfer rule holding unit 130 in order to checka destination of the received CAN frame (step S4).

Next, the transfer control unit 140 determines, on the basis of thetransfer rule information, whether the CAN-ID of the CAN frame is to betransferred to the second CAN bus (step S5), If so, the transfer controlunit 140 transmits the CAN frame to the C communication unit 110 b (stepS6).

The C communication unit 110 b that has received the CAN frame transmitsthe CAN frame to the second CAN bus with the transmission section 112 b(step S7).

If the transfer control unit 140 determines in step S5 that the CAN-IDof the CAN frame is not to be transferred to the second CAN bus, orafter the CAN frame is transmitted in step S6, the transfer control unit140 determines whether the CAN-ID of the CAN frame is to be transferredto the second network (E network) (step S8). If the transfer controlunit 140 determines in step S8 that the CAN-ID is not to be transferredto the E network, the gateway 100 ends the transfer process.

If determining in step S8 that the CAN-ID of the CAN frame (the CANframe received in step S2) is to be transferred to the E network, thetransfer control unit 140 obtains and refers to the priority transferlist held by the transfer rule holding unit 130 in order to checkwhether the CAN frame has priority (promptness) in transfer (step S9).The transfer control unit 140 then determines whether the CAN-ID of theCAN frame is described in the priority transfer list (a CAN-ID havingpriority in transfer) (step S10).

If determining in step S10 that the CAN-ID of the CAN frame is a CAN-IDhaving priority in transfer, the transfer control unit 140 generates anE frame including, in a payload, CAN frame information regarding the CANframe and a CAN flag that has been turned on (step S11). A MAC address(a MAC address of a destination E-ECU) indicated in a correspondingpiece of transfer identification information in the priority transferlist is set as a destination MAC address in a header of the E frame. TheMAC address of the gateway 100, for example, is set as a source MACaddress in the header of the E frame.

Next, the transfer control unit 140 transmits the E frame generated instep S11 to the E communication unit 120 in a prioritized manner(immediate transmission) in order to transmit the E frame to thedestination (step S12). Upon receiving the E frame, the transmissionsection 122 of the E communication unit 120 transmits the E frame (stepS13).

If determining in step S10 that the CAN-ID of the CAN frame does nothave priority in transfer, the transfer control unit 140 stores the CANframe information including the CAN-ID, size, and data of the CAN framein the buffer (the storage medium included in the gateway 100) whileassociating the CAN frame information with the destination (MAC address)selected on the basis of the transfer rule information (step S14).

After step S12 or S14, the transfer control unit 140 determines whetherthe certain condition relating to the number of CAN frames received issatisfied, that is, whether N pieces of CAN frame information whosedestinations are the same have been accumulated in the buffer (stepS15).

If determining in step S15 that the certain condition is satisfied(i.e., N pieces of CAN frame information whose destinations are the samehave been accumulated), the transfer control unit 140 generates an Eframe including, in a payload, a CAN flag that has been turned on andthe N pieces of CAN frame information whose destinations are the same(step S16). A MAC address of the destination based on the transfer ruleinformation is set as a destination MAC address in a header of the Eframe, and the MAC address of the gateway 100, for example, is set as asource address in the header.

Next, the transfer control unit 140 transmits the E frame generated instep S16 to the E communication unit 120 in order to transmit the Eframe to the destination (step S17). Upon receiving the E frame, thetransmission section 122 of the E communication unit 120 transmits the Eframe (step S18).

If the transfer control unit 140 determines in step S15 that the certaincondition is not satisfied, the gateway 100 ends the transfer processand waits for a next CAN frame to be received.

1.6 Advantageous Effects Produced by First Embodiment

In the vehicle network system 10 according to the first embodiment, ifthe gateway 100 receives a CAN frame transmitted from a C-ECU to a CANbus in the vehicle networks including the first and second networkswhose communication protocols are different from each other, the gateway100 transfers the frame by transmitting information (CAN frameinformation) such as data regarding the CAN frame with an E-ECU set as adestination under a certain condition. During the transfer, the gateway100 transmits an E frame including CAN frame information regarding aplurality of received CAN frames whose destinations are the same E-ECUand a CAN flag that has been turned on to the E-ECU. As a result,transmission efficiency can improve. In addition, if the gateway 100receives a CAN frame having a particular ID, the gateway 100 transfersthe frame by immediately transmitting an E frame including CAN frameinformation regarding the CAN frame to a particular E-ECU. As a result,the content of a CAN frame or the like having a particular ID can bepromptly transmitted to an E-ECU. That is, although the vehicle networksystem 10 employs a transfer method with which a delay can be caused intransmission of information regarding a frame in order to increasetransmission efficiency of the information, important information can bepromptly transmitted from a C-ECU to an E-ECU by, for example, setting aCAN-ID of an important CAN frame as a particular ID.

Second Embodiment

An example will be described hereinafter in which the gateway 100 of thevehicle network system 10 (refer to FIG. 1) according to the firstembodiment is partly modified.

2.1 Gateway 100 a

A vehicle network system according to the present embodiment includes agateway 100 a having the same configuration as the gateway 100 (refer toFIG. 6) of the vehicle network system 10 according to the firstembodiment. A function of a transfer control unit 140 of the gateway 100a, however, is partly different from that of the transfer control unit140 of the gateway 100. In the vehicle network system according to thepresent embodiment, the same components as those according to the firstembodiment are given the same reference numerals as in the firstembodiment, and description thereof is omitted as necessary. The vehiclenetwork system according to the present embodiment is the same as thevehicle network system 10 according to the first embodiment, unlessotherwise specified.

If the transfer control unit 140 of the gateway 100 according to thefirst embodiment determines that a plurality of sequentially receivedCAN frames are to be transmitted to the second network, the transfercontrol unit 140 constructs an E frame obtained by connecting CAN frameinformation regarding a plurality of (e.g., the predetermined number,namely N) CAN frames whose destinations selected on the basis of thereference information (the transfer rule information, etc.) are the same(e.g., the destinations are a MAC address of the same E-ECU) andincluding the connected CAN frame information in a payload (refer toFIG. 7).

If the transfer control unit 140 of the gateway 100 a determines that aplurality of sequentially received CAN frames are to be transmitted tothe second network, on the other hand, the transfer control unit 140constructs an E frame obtained by connecting CAN frame informationregarding a plurality of (e.g., the predetermined number, namely N) CANframes and including the connected CAN frame information in a payloadregardless of destinations selected on the basis of the referenceinformation (the transfer rule information, etc.) and causes thetransmission section 122 to transmit the E frame to the second network.The configuration of the E frame at this time, for example, is asillustrated in FIG. 12.

FIG. 12 illustrates an image of the gateway 100 a transmitting an Eframe on the basis of a plurality of received CAN frames (first to N-thCAN frames). A payload of the E frame to be transmitted includes, forexample, a predetermined number of, namely N, pieces of CAN frameinformation (CAN-IDs, size, and data) to which destination MAC addresses(i.e., MAC addresses of destination E-ECUs) indicating destinations areadded. Data regarding the N pieces of CAN frame information is thecontent (data) of data fields or the like of the received N CAN frames.For example, broadcast addresses are set as destination MAC addresses ina header of the E frame, the MAC address of the gateway 100 a is set asa source MAC address in the header of the E frame, and a CAN flag thathas been turned on, which indicates that CAN frame information isincluded, is set in the payload of the E frame. The E frame includingthe N pieces of CAN frame information to which the destination MACaddresses are added illustrated in FIG. 12, for example, is to bereceived by the E-ECUs (the E-ECUs 200 a to 200 c, etc.) through theE-hub 400. When the E-hub 400 has received an E frame whose destinationMAC address is a broadcast address, the E-hub 400 outputs the E framefrom all ports other than a port with which the E frame has beenreceived (i.e., a connection terminal for a cable). The E-ECUs canextract the CAN frame information intended therefor included in the Eframe by comparing the destination MAC addresses in the payload of the Eframe with MAC addresses thereof.

The E-hub 400 that has received an E frame including a plurality ofpieces of CAN frame information corresponding to a plurality ofdestinations such as that illustrated in FIG. 12 may have a divisiontransfer function of dividing the plurality of pieces of CAN frameinformation in a payload of the E frame for destinations (destinationMAC addresses) and outputting, for each destination, an E frame from aport leading to an E-ECU indicated by the destination while includingCAN frame information corresponding to the destination in a payload andsetting the destination MAC address as a destination MAC address in aheader. An E-hub having such a division transfer function may determinewhether to implement the division transfer function or a generalfunction of transferring an E frame, for example, depending on whether aCAN flag in a payload of an E frame is on. If an E-hub having thedivision transfer function and a MAC address is connected to the secondnetwork, it is effective for the gateway 100 a to set, when transmittingan E frame, not a broadcast address but a MAC address of the E-hub as adestination MAC address in a header of the E frame. If a destinationindicated by the destination identification information in the transferrule information (refer to FIG. 8) is an address indicating a subnetworkto which a plurality of E-ECUs of the same type are connected, thegateway 100 a may construct, with the configuration illustrated in FIG.12, an E frame including a plurality of pieces of CAN frame informationwhose destinations are the E-ECUs of the same type and transmit the Eframe to the second network.

2.2 Advantageous Effects Produced by Second Embodiment

In the vehicle network system according to the second embodiment, thegateway 100 a transmits an E frame including CAN frame informationregarding a plurality of CAN frames to the second network on the basisof the plurality of CAN frames received from a bus of the first networkregardless of destinations. As a result, transmission efficiency canimprove to some degree.

Other Embodiments

The first and second embodiments have been described above as examplesof the technique in the present disclosure. The technique in the presentdisclosure, however, is not limited to this and may be applied toembodiments obtained by performing modification, replacement, addition,omission, and the like as necessary. The following modifications, forexample, are included in an aspect of the present disclosure.

(1) The vehicle network system according to each of the aboveembodiments may include an E-hub connected to the second network andhaving the division transfer function in addition to the E-hub 400 thatdoes not have the division transfer function. For example, the gateway100 a according to the second embodiment may sequentially receive CANframes and transmit the E frame illustrated in FIG. 12 to the E-hub 400.The E-hub 400 may then transfer the E frame to the E-hub having thedivision transfer function, and the E-hub having the division transferfunction may divide a plurality of pieces of CAN frame informationincluded in the E frame and transmit, to each destination, an E frameincluding CAN frame information corresponding to an E-ECU as thedestination.

(2) Although the vehicle network system has been described in the aboveembodiments, the above-described devices such as the gateways, the ECUs(the E-ECUs and the C-ECUs) and the E-hub may also be used for variousnetwork communication systems such as robots and industrial machines.

(3) In the above embodiments, the vehicle networks include the first andsecond networks. The first network transmits a CAN frame (data frame) inaccordance with the CAN protocol using a CAN bus, and the second networktransmits an E frame (Ethernet (registered trademark) frame) inaccordance with the Ethernet (registered trademark) protocol. The CANprotocol may be interpreted in a broad sense and include derivativeprotocols such as CAN-open, which is used for a system incorporated intoan automated system, time-triggered CAN (TTCAN), and CAN with flexibledata rate (CAN FD). A data frame in the CAN protocol may have anenhanced ID format as well as a standard ID format. An Ethernet(registered trademark) frame may be, for example, a frame of Ethernet(registered trademark) version 2 or a frame specified in IEEE 802.3. TheEthernet (registered trademark) protocol may be interpreted in a broadsense and include derivative protocols such as Ethernet (registeredtrademark) audio video bridging (AVB) according to IEEE 802.1, Ethernet(registered trademark) time-sensitive networking (TSN) according to IEEE802.1, Ethernet (registered trademark) industrial protocol(Ethernet/IP), and Ethernet (registered trademark) for ControlAutomation Technology (EtherCAT; registered trademark). In the firstnetwork, a frame of a first type (e.g., a CAN frame, etc.) may betransmitted through a bus in accordance with a first communicationprotocol, and a frame of a second type (e.g., an E frame, etc.) may betransmitted in accordance with a second communication protocol, which isdifferent from the first communication protocol. In this case, the firstcommunication protocol is the CAN protocol, for example, but may belocal interconnect network (LIN), Media Oriented Systems Transport(MOST; registered trademark), or FlexRay (registered trademark),instead. The second communication protocol is the Ethernet (registeredtrademark) protocol, for example, but may be a BroadR-Reach protocol,instead. Through the vehicle networks including the first and secondnetworks, information that has been transmitted by an electronic controlunit of a first type (e.g., a C-ECU) connected to the first network canbe transmitted to an electronic control unit of a second type (e.g., anE-ECU) connected to the second network. Ethernet (registered trademark)described in the above embodiments has a higher communication speed thanCAN. In this sense, the second communication protocol may be one ofvarious protocols having a higher communication speed than the firstcommunication protocol. In addition, although a frame of the second type(e.g., an E frame) includes an identification flag (e.g., a CAN flag)for determining whether a payload of the frame of the second typeincludes data and the like (e.g., CAN frame information) regarding aframe of the first type (e.g., a CAN frame) to be transmitted to thesecond network in the above embodiments, the identification flag may beincluded in a header of the frame of the second type, instead. Thegateway 100, for example, may include a CAN flag in a header of an Eframe. As a result, whether a payload includes CAN frame information canbe determined just by referring to the header of the E frame, and whenthe payload of the E frame has been encrypted, for example, processingcan be simplified (omission of decryption, etc.). For example, a bit fordetermining whether a destination MAC address in a header of an E frameis a global MAC address may be used as a CAN flag (e.g., a valueindicating a local MAC address is treated as a CAN flag that has beenturned on). Alternatively, for example, a CAN flag may be provided for afield of a type in a header of an E frame. Alternatively, for example,the gateway 100 may include a CAN flag in both a header and a payload ofan E frame.

(4) Although an example in which the gateway 100 is connected to theEthernet (registered trademark) 20 d in relation to the second networkhas been described in the above embodiment, the gateway 100 may includeports connected to a plurality of Ethernet (registered trademark)cables, instead. That is, the gateway 100 may be integrated with theE-hub 400. In this case, the gateway 100 can select a destination of aCAN frame on the basis of the reference information such as the transferrule information, identify a port connected to a cable corresponding tothe destination in a MAC address table, for example, and transmit an Eframe to the port. More specifically, the determination section 141 ofthe transfer control unit 140 of the gateway 100 refers to the referenceinformation (e.g., the transfer rule information and the MAC addresstable, etc.) in which a plurality of cables and CAN-IDs are associatedwith each other and selects, on the basis of a CAN-ID of a CAN framereceived by the reception section 111 a or 111 b, one of the pluralityof cables as a destination of CAN frame information, which is data andthe like regarding the CAN frame to be transmitted to the secondnetwork. The transfer control unit 140 then constructs, with the frameconstruction section 142, an E frame including CAN frame information,which is data and the like regarding a plurality of CAN frames for whichthe same cable has been selected by the determination section 141 as adestination of CAN frame information and controls the transmissionsection 122 in such a way as to output the E frame to the selectedcable, in order to achieve transmission of the E frame to the secondnetwork. Alternatively, the gateway 100 may select a plurality of cablesand output, to the plurality of cables, E frames having the same payloadincluding one or plurality of pieces of CAN frame information. In thiscase, the gateway 100 need not have a function as a switch (switchinghub) and may output the E frames to all the cables withoutdistinguishing destination MAC addresses of the E frames.

(5) In the above embodiment, if the certain condition relating to thenumber of CAN frames sequentially received is satisfied (e.g., N piecesof CAN frame information whose destinations are the same have beenaccumulated in the buffer), the gateway 100 transmits an E frameincluding CAN frame information regarding the CAN frames to the secondnetwork. A certain condition relating to time may be used in additionto, or instead of, this certain condition. That is, the gateway 100 maycount time, and, if the certain condition relating to time is satisfied,an E frame including CAN frame information that has been accumulated inthe buffer, whose destinations are the same, and that has not beentransmitted may be generated, and the transmission section 122 maytransmit the E frame to the second network. The certain conditionrelating to time, for example, is a condition that is satisfied when apredetermined period of time has elapsed since a previous E frame wasoutput.

(6) Although the gateway 100 is connected to a plurality of CAN buses inrelation to the first network in the above embodiment, the gateway 100may be connected to a single CAN bus, instead. In this case, informationregarding sources may be omitted, for example, in the transfer ruleinformation and the priority transfer list.

(7) Although an example in which CAN frame information included in an Eframe transmitted by the gateway 100 includes a CAN-ID, size, and datain the above embodiment, CAN frame information may include only data,instead.

(8) Procedures of the various processes described in the aboveembodiments (e.g., the certain procedure illustrated in FIGS. 10 and 11,etc.) need not necessarily be performed in the above-described order.The order in which the procedures are performed may be switched, aplurality of procedures may be performed in parallel with each other, ora part of a procedure may be omitted, instead.

(9) The devices such as the gateways, the ECUs, and the E-hub in theabove embodiments may include other hardware components such as a harddisk device, a display, a keyboard, and a mouse. In addition, a programstored in a memory may be executed by a processor in order to achieve afunction of each device in a software manner, or dedicated hardware (adigital circuit, etc.) may achieve the function. Distribution offunctions of the components of each device may also be changed.

(10) Some or all of the components of each device in the aboveembodiments may be configured by a single system large-scale integration(LSI) circuit. A system LSI circuit is a super-multifunctional LSIcircuit fabricated by integrating a plurality of components on a singlechip and is specifically a computer system including a microprocessor, aROM, and a RAM. The RAM stores a computer program. The system LSIcircuit achieves functions thereof when the microprocessor operates inaccordance with the computer program. Alternatively, each of thecomponents of each device may be achieved by a single chip, or some orall of the components of each device may be achieved by a single chip.Although system LSI has been used here, integrated circuit (IC), LSI,super LSI, or ultra LSI might be used depending on a degree ofintegration. In addition, some or all of the components of each devicein the above embodiments need not necessarily be achieved by an LSIcircuit and may be achieved by a dedicated circuit or a general-purposeprocessor, instead. A field-programmable gate array (FPGA) that can beprogrammed after an LSI circuit is fabricated or a reconfigurableprocessor capable of reconfiguring connections and settings of circuitcells inside an LSI circuit may be used, instead. Furthermore, it isneedless to say that if a technique for fabricating an integratedcircuit that replaces LSI becomes available as a result of evolution ofsemiconductor technologies or derivative techniques, the functionalblocks may be integrated using the technique. Application ofbiotechnology is one of such possibilities.

(11) Some or all of the components of each device may be achieved by anIC card or a separate module removably attached to each device. The ICcard or the module is a computer system including a microprocessor, aROM, and a RAM. The IC card or the module may include thesuper-multifunctional LSI circuit. The IC card or the module achievesfunctions thereof when the microprocessor operates in accordance with acomputer program. The IC card or the module may be tamper-resistant.

(12) An aspect of the present disclosure may be, for example, a transfermethod including the entirety or a part of the processing procedureillustrated in FIGS. 10 and 11 or the like. For example, the transfermethod is used by a gateway connected to a bus of a first networkthrough which a frame of a first type is transmitted in accordance witha first communication protocol using the bus and a second networkthrough which a frame of a second type is transmitted in accordance witha second communication protocol, which is different from the firstcommunication protocol. The transfer method includes a reception step(e.g., step S2) of sequentially receiving the frame of the first typefrom the bus, a determination step (e.g., step S8) of determiningwhether to transmit data regarding the frame of the first type receivedin the reception step to the second network, and a transmission step(e.g., steps S16 to S18) of transmitting, to the second network, theframe of the second type including data regarding a plurality of framesof the first type determined in the determination step to be transmittedto the second network. In addition, an aspect of the present disclosuremay be a program (computer program) for achieving this method using acomputer or a digital signal including the computer program. Forexample, an aspect of the present disclosure may be a program forperforming a certain transfer process including the reception step, thedetermination step, and the transmission step of the transfer method. Inaddition, an aspect of the present disclosure may be a computer-readablerecording medium storing the computer program or the digital signal,such as a flexible disk, a hard disk, a CD-ROM, a magneto-optical (MO)disk, a digital versatile disc (DVD), a DVD-ROM, a DVD-RAM, a Blu-rayDisc (BD; registered trademark), or a semiconductor memory. In addition,an aspect of the present disclosure may be the digital signal stored inthe recording medium. In addition, an aspect of the present disclosuremay be the computer program or the digital signal transmitted through anelectrical communication line, a wireless or wired communication line, anetwork typified by the Internet, datacasting, or the like. In addition,an aspect of the present disclosure may be a computer system including amicroprocessor and a memory. The memory may store the computer program,and the microprocessor may operate in accordance with the computeprogram. In addition, an aspect of the present disclosure may beimplemented by another independent computer system by storing theprogram or the digital signal in the recording medium and transportingthe recording medium or by transporting the program or the digitalsignal through the network or the like.

(13) The scope of the present disclosure also includes modes obtained bycombining the components and the functions described in the aboveembodiments and modifications in any manner.

The present disclosure can be used to transmit information transmittedfrom an ECU connected to a bus of a first network such as a CAN toanother ECU through a second network such as Ethernet (registeredtrademark).

What is claimed is:
 1. A gateway device connected to a first networkthrough which a frame of a first type is transmitted using the firstnetwork in accordance with a first communication protocol and connectedto a second network through which a frame of a second type istransmitted in accordance with a second communication protocol, which isdifferent from the first communication protocol, the gateway devicecomprising: a receiver that sequentially receives frames of the firsttype from the first network; a processor that determines whether totransmit data regarding the frames of the first type received by thereceiver to the second network; and a transmitter that transmits, to thesecond network, the frame of the second type including data regarding aplurality of the frames of the first type determined by the processor tobe transmitted to the second network, wherein the first network and thesecond network are vehicle networks, wherein the gateway device isconnected to an Ethernet (registered trademark) cable included in thesecond network, wherein the first communication protocol is a controllerarea network protocol, wherein the second communication protocol is anEthernet (registered trademark) protocol, wherein the frame of the firsttype includes a controller area network identifier and, in a data field,data, wherein the frame of the second type is an Ethernet (registeredtrademark) frame including an Ethernet (registered trademark) header anda payload, wherein the transmitter transmits the frame of the secondtype to the second network by outputting the frame of the second type tothe Ethernet (registered trademark) cable, and wherein the transmittertransmits the frame of the second type including the data regarding theplurality of the frames of the first type when a condition relating to anumber of frames of the first type received by the receiver issatisfied.
 2. The gateway device according to claim 1, wherein theprocessor determines, on a basis of the controller area networkidentifier of each of the frames of the first type received by thereceiver, whether to transmit data regarding the frames of the firsttype to the second network.
 3. The gateway device according to claim 2,wherein the processor refers to reference information in which aplurality of destinations is associated with controller area networkidentifiers and selects, on the basis of the controller area networkidentifier of each of the frames of the first type received by thereceiver, one of the plurality of destinations as a destination of thedata regarding the plurality of the frames of the first type to betransmitted to the second network, and wherein the transmittertransmits, to the second network, the frame of the second type includingthe data regarding the plurality of the frames of the first type whosedestinations selected by the processor are same.
 4. The gateway deviceaccording to claim 3, wherein the frame of the second type transmittedby the transmitter includes destination information indicating the samedestinations selected by the processor.
 5. The gateway device accordingto claim 4, wherein, in the reference information, a plurality of mediaaccess control addresses as the plurality of destinations is associatedwith the controller area network identifiers, and wherein the frame ofthe second type transmitted by the transmitter includes the dataregarding the plurality of the frames of the first type having the samedestinations selected by the processor in the payload, a media accesscontrol address, which is the same destinations, as the destinationinformation, and a destination media access control address in anEthernet (registered trademark) header.
 6. The gateway device accordingto claim 3, wherein the gateway device is connected to a plurality ofbuses of the first network, wherein the plurality of destinations, theplurality of buses, and the controller area network identifiers areassociated in the reference information, and wherein the processorrefers to the reference information and selects, on the basis of thecontroller area network identifier and a source bus of each of theframes of the first type received by the receiver, one of the pluralityof destinations as the destination of the data regarding the pluralityof the frames of the first type to be transmitted to the second network.7. The gateway device according to claim 2, wherein the processor refersto reference information in which a plurality of destinations isassociated with controller area network identifiers and selects, on thebasis of the controller area network identifier of each of the frames ofthe first type received by the receiver, one of the plurality ofdestinations as a destination of the data regarding the plurality of theframes of the first type to be transmitted to the second network, andwherein the transmitter transmits the frame of the second type includingthe data regarding the plurality of the frames of the first typedetermined by the processor to be transmitted to the second network andtransmits destination information indicating the destination selected bythe processor in the payload.
 8. The gateway device according to claim2, wherein the gateway device is connected to a plurality of Ethernet(registered trademark) cables, wherein the processor refers to referenceinformation in which the plurality of cables is associated withcontroller area network identifiers and selects, on the basis of thecontroller area network identifier of each of the frames of the firsttype received by the receiver, one of the plurality of Ethernet(registered trademark) cables as a destination of the data regarding theplurality of the frames of the first type to be transmitted to thesecond network, and wherein the transmitter transmits the frame of thesecond type including the data regarding the plurality of the frames ofthe first type whose Ethernet (registered trademark) cables selected bythe processor as destinations are same, to the one of the plurality ofEthernet (registered trademark) cables.
 9. The gateway device accordingto claim 1, wherein, in the frame of the second type, the data regardingthe plurality of the frames of the first type determined by theprocessor to be transmitted to the second network is arranged in orderof predetermined priority levels of controller area network identifiersbased on controller area network identifiers of the plurality of theframes of the first type.
 10. The gateway device according to claim 1,wherein, in the frame of the second type, the data regarding theplurality of the frames of the first type determined by the processor tobe transmitted to the second network is arranged in order of receptionby the receiver.
 11. The gateway device according to claim 1, wherein,when the controller area network identifier of one of the frames of thefirst type received by the receiver is a particular identifier, thetransmitter transmits, to the second network, a frame of the second typeincluding data regarding the one of the frames of the first type havingthe particular identifier even when the condition is not satisfied. 12.The gateway device according to claim 11, wherein, when transmitting theframe of the second type including the data regarding the one of theframes of the first type having the particular identifier, thetransmitter: transmits the frame of the second type and includes dataregarding a second one of the frames of the first type that does nothave the particular identifier and that has been determined by theprocessor to be transmitted to the second network and has not yet beentransmitted; or transmits another frame of the second type including thedata regarding the second one of the frames of the first type that doesnot have the particular identifier and that has been determined by theprocessor to be transmitted to the second network and has not yet beentransmitted.
 13. The gateway device according to claim 1, wherein thetransmitter transmits the frame of the second type when a conditionrelating to time is satisfied as a result of counting of the time. 14.The gateway device according to claim 1, wherein the plurality of theframes of the first type determined by the processor to be transmittedto the second network include a same destination.
 15. A vehicle networksystem, comprising: a plurality of electronic control units of a firsttype connected to a first network through which a frame of a first typeis transmitted in accordance with a first communication protocol; anelectronic control unit of a second type connected to a second networkthrough which a frame of a second type is transmitted in accordance witha second communication protocol, which is different from the firstcommunication protocol; and a gateway device connected to the firstnetwork and the second network, wherein the gateway device includes: areceiver that sequentially receives frames of the first type from thefirst network; a processor that determines whether to transmit dataregarding the frames of the first type received by the receiver to thesecond network; and a transmitter that transmits, to the second network,the frame of the second type including data regarding a plurality of theframes of the first type determined by the processor to be transmittedto the second network, wherein the first network and the second networkare vehicle networks, wherein the gateway device is connected to anEthernet (registered trademark) cable included in the second network,wherein the first communication protocol is a controller area networkprotocol, wherein the second communication protocol is an Ethernet(registered trademark) protocol, wherein the frame of the first typeincludes a controller area network identifier and, in a data field,data, wherein the frame of the second type is an Ethernet (registeredtrademark) frame including an Ethernet (registered trademark) header anda payload, wherein the transmitter transmits the frame of the secondtype to the second network by outputting the frame of the second type tothe Ethernet (registered trademark) cable, and wherein the transmittertransmits the frame of the second type including the data regarding theplurality of the frames of the first type when a condition relating to anumber of frames of the first type received by the receiver issatisfied.
 16. A transfer method of a gateway device connected to afirst network through which a frame of a first type is transmitted usingthe first network in accordance with a first communication protocol andconnected to a second network through which a frame of a second type istransmitted in accordance with a second communication protocol, which isdifferent from the first communication protocol, the transfer methodcomprising: sequentially receiving frames of the first type from thefirst network; determining, by a processor, whether to transmit dataregarding the frames of the first type received in the sequentiallyreceiving to the second network; and transmitting, to the secondnetwork, the frame of the second type including data regarding aplurality of the frames of the first type determined by the processor inthe determining to be transmitted to the second network, wherein thefirst network and the second network are vehicle networks, wherein thegateway device is connected to an Ethernet (registered trademark) cableincluded in the second network, wherein the first communication protocolis a controller area network protocol, wherein the second communicationprotocol is an Ethernet (registered trademark) protocol, wherein theframe of the first type includes a controller area network identifierand, in a data field, data, wherein the frame of the second type is anEthernet (registered trademark) frame including an Ethernet (registeredtrademark) header and a payload, wherein the frame of the second type istransmit to the second network by being output to the Ethernet(registered trademark) cable, and wherein the frame of the second typeis transmit to the second network and includes the data regarding theplurality of the frames of the first type when a condition relating to anumber of frames of the first type received by the sequentiallyreceiving is satisfied.
 17. A non-transitory computer-readable recordingmedium storing a program for causing a gateway device that is connectedto a first network through which a frame of a first type is transmittedusing the first network in accordance with a first communicationprotocol and connected to a second network through which a frame of asecond type is transmitted in accordance with a second communicationprotocol, which is different from the first communication protocol, toperform operations comprising: sequentially receiving frames of thefirst type from the first network; determining whether to transmit dataregarding the frames of the first type received in the receiving to thesecond network; and transmitting, to the second network, the frame ofthe second type including data regarding a plurality of the frames ofthe first type determined in the determining to be transmitted to thesecond network, wherein the first network and the second network arevehicle networks, wherein the gateway device is connected to an Ethernet(registered trademark) cable included in the second network, wherein thefirst communication protocol is a controller area network protocol,wherein the second communication protocol is an Ethernet (registeredtrademark) protocol, wherein the frame of the first type includes acontroller area network identifier and, in a data field, data, whereinthe frame of the second type is an Ethernet (registered trademark) frameincluding an Ethernet (registered trademark) header and a payload,wherein the frame of the second type is transmit to the second networkby being output to the Ethernet (registered trademark) cable, andwherein the frame of the second type is transmit to the second networkand includes the data regarding the plurality of the frames of the firsttype when a condition relating to a number of frames of the first typereceived by the sequentially receiving is satisfied.